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Numerická simulace a vizualizace vytváření syntetizovaného proudu
Trávníček, Zdeněk ; Vogel, Jiří ; Vít, T.
The paper presents the results of numerical and experimental investigations of a synthetic jet generation. The experiments were performed in air by means of flow visualization and hot-wire anemometry. The subsequent numerical simulation was performed using the commercial code FLUENT. The geometry, boundary conditions, and material properties of the numerical simulation were defined according to the real experimental situation.
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Smoke visualization of jet and wake flows
Trávníček, Zdeněk
Flow visualization, as a part of experimental fluid mechanics, is a typical initial step of many experimental studies. It can contribute significantly to the understanding of mechanisms involved in flow fields. Moreover, it can be helpful in the selection of the flow parameters and regions of interest for local and detail point measurements. The visualization can be very beneficial for a precise adjustment of a chosen flow field pattern in a test section if alternative flow field modes are possible. Typical case is a bistable and hysteretic behavior of complex flows. The paper shows a few cases of complex jet and wake flows, namely impinging jets from standard and special nozzles (round and slot nozzles, annular nozzle with a fluidic or acoustic control, two-slot nozzle, and slot nozzle with the Coanda effect), and a non-isothermal wake flow behind a cylinder in the cross flow.
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Heat/mass transfer of axi-symmetric, actively controlled impinging jet
Trávníček, Zdeněk ; Peszynski, K.
Annular nozzle has been equipped by a fluidic control of a jet flow state. The jet flow can be either focused along the nozzle axis or spread out of nozzle axis. Nozzle geometry aimed an enhancement of head and mass transfer on exposed wall by means of active flow control. A visualization of the jet flow was performed, mass transfer was measured by naphthalene sublimation method, and heat/ mass transfer analogy was used.
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Vícenásobné stísněné impaktní proudy s příčným odvodem tekutiny
Dvořák, Rudolf ; Trávníček, Zdeněk ; Vogel, J.
Confined impinging multiple gaseous jets have extensive technological applications, being used for drying, heating or cooling (as eg. internal cooling of gas turbine blades). Their applicability, cooling efficiency, etc. depend heavily on the way the fluid is withdrawn from the exposed area. Good CFD results are rare, and numerous experimental results, as well as any generalization of the empirical findings require a well founded knowledge of the flow structure. The paper reports on the results achieved so far in the investigation of this problem.
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Jet flowing into a cavity
Dvořák, Rudolf ; Trávníček, Zdeněk ; Vogel, J.
The flow field in a half-open space (cavity) generated by an impinging jet and a fountain jet of the spent fluid has been described. Results of numerical modelling (based on FLUENT) are presented, and a twodimensional test section for flow visualization and PIV measurements manufactured in the Institute of Thermomechanics has also been described.
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